To transfer articles in a clean room or the like, a scholar arm is used if it is critical to avoid raising dust. Otherwise a slide fork is used. The structure of the slide fork is described in, for example, the Unexamined Japanese Patent Application Publication (Tokkai-Hei) No. 10-35819. In this slide fork, one end of a driving member such as chains or belts is fixed to a top portion. The other end is fixed to a base portion. Guide wheels such as sprockets or pulleys are arranged between these ends. In this case, the guide wheels are required at a leading end of a middle portion, and the chains or belts extend up to a leading end of the top portion. Accordingly, when the slide fork is advanced, dust may be raised from shelves or articles by the guide wheel arranged at the leading end of the middle portion.
With the increased sizes of semiconductor and liquid crystal substrates, the scholar arm may fail to provide a sufficient capability of transferring these articles. However, if the slide fork is used to transfer the articles, dust is disadvantageously raised from the shelves or articles.